According to an article in The Nation magazine, the U.S. Ninth Infantry Division during the Vietnam War in an what is called Operation Speedy Express had the highest number of kills (body count) relative to the number of U.S. personnel lost and at the same time the lowest number of verified enemy weapons per kill (dead Vietnamese). Now, it isn't that it just had a high body count. It was some 10,899 while losing 267 Americans and capturing only 748 weapons. Think about that. The average for other divisions was much lower with many more weapons relative to supposed enemies killed.
Here's what happened. The U.S. Ninth Infantry Division was run by monsters who mowed down unarmed peasants often at night using night vision from helicopters equipped with large caliber machine guns. If the peasants, who were naturally afraid of the helicopters since people were constantly being killed by the Americans, ran, they'd be killed. They'd be killed in the day if they didn't run but were just wearing black. They were killed just because the U.S. wanted dead bodies they could call the enemy to make it seem at home in America as if the U.S. were winning the war and, frankly, just to kill people.
"," by Nick Turse. The Nation. (December 1, 2008 print edition). November 13, 2008.
Let's not forget that the same thing applied in Korea as well. Unarmed refugees running away from the fighting toward the American or South Korean lines were mowed down. Take no prisoners. If they're running, even if they are running from bombing, kill them. That was how it was.
The people who fought in WWII taught the people who fought in Korea. The people who fought in Korea taught the people who fought in Vietnam. The people who fought in Vietnam taught the people who fought in all the little dirty wars up to the Gulf War and then Afghanistan and then Iraq and then ...